[FFmpeg-devel] [PATCH] lavc/vp9: set update_map to 0 when segmentation.enabled is 0

[Ronald S. Bultje]

Hi,

On Wed, May 22, 2024 at 10:36 AM Hendrik Leppkes <h.leppkes at gmail.com>
wrote:

> On Thu, Feb 29, 2024 at 7:19 AM llyyr <llyyr at yukari.in> wrote:
> >
> > segmentation.update_map is never reset to 0 on a new frame, and retains
> > the value from the previous frame. This bugs out a bunch of hwaccel
> > drivers when segmentation.enabled is 0 but update_map isn't because
> > they don't ignore values behind switches. We also do this for vp8* so
> > this commit is just mirroring the vp8 logic.
> >
> > This fixes an issue with certain samples** that causes blocky
> > artifacts with vaapi and d3d11va (as far as known hwaccel drivers go).
> > Mesa worked around*** this by ignoring this field if
> > segmentation.enabled is 0, but d3d11va still doesn't work.
> >
> > *
> https://git.ffmpeg.org/gitweb/ffmpeg.git/blob/HEAD:/libavcodec/vp8.c#l811
> > ** https://github.com/mpv-player/mpv/issues/13533
> > *** https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/27816
> >
> > Signed-off-by: llyyr <llyyr at yukari.in>
> > ---
> >  libavcodec/vp9.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/libavcodec/vp9.c b/libavcodec/vp9.c
> > index 855936cdc1c7..4a628625131e 100644
> > --- a/libavcodec/vp9.c
> > +++ b/libavcodec/vp9.c
> > @@ -717,6 +717,8 @@ static int decode_frame_header(AVCodecContext *avctx,
> >                  s->s.h.segmentation.feat[i].skip_enabled =
> get_bits1(&s->gb);
> >              }
> >          }
> > +    } else {
> > +        s->s.h.segmentation.update_map = 0;
> >      }
> >
> >      // set qmul[] based on Y/UV, AC/DC and segmentation Q idx deltas
> >
> > base-commit: d263fce2b209e86a5a1e8f1b6aa33430ecc2c187
> > --
>
> Change LGTM.
> I was debugging the same issue today, and found the same problem with
> some hwaccels not properly ignoring update_map when segmentation is
> disabled.
>
> Will apply soon if there are no further comments.
>

Is fine, please apply.

Ronald